49 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2 3/*4 * Copyright 2020 Google LLC.5 */6 7#include <errno.h>8#include <linux/bpf.h>9#include <linux/if_ether.h>10#include <linux/ip.h>11#include <bpf/bpf_helpers.h>12 13struct {14 __uint(type, BPF_MAP_TYPE_ARRAY);15 __uint(max_entries, 1);16 __type(key, __u32);17 __type(value, __u32);18} test_result SEC(".maps");19 20SEC("cgroup_skb/egress")21int load_bytes_relative(struct __sk_buff *skb)22{23 struct ethhdr eth;24 struct iphdr iph;25 26 __u32 map_key = 0;27 __u32 test_passed = 0;28 29 /* MAC header is not set by the time cgroup_skb/egress triggers */30 if (bpf_skb_load_bytes_relative(skb, 0, ð, sizeof(eth),31 BPF_HDR_START_MAC) != -EFAULT)32 goto fail;33 34 if (bpf_skb_load_bytes_relative(skb, 0, &iph, sizeof(iph),35 BPF_HDR_START_NET))36 goto fail;37 38 if (bpf_skb_load_bytes_relative(skb, 0xffff, &iph, sizeof(iph),39 BPF_HDR_START_NET) != -EFAULT)40 goto fail;41 42 test_passed = 1;43 44fail:45 bpf_map_update_elem(&test_result, &map_key, &test_passed, BPF_ANY);46 47 return 1;48}49